December 19, 2007

You have touched me with the depth and eloquence of your tributes to his life and work. I particularly want to thank my dear step-son, Nick Sagan, Joel Schlosberg, and Bryan and Dave of the Celebrating Sagan website for creating cyber-communities where those of us who remember Carl can gather.

As the years pass, more and more of what he taught is affirmed and his influence grows.

Carl began working with NASA on missions to the planets in 1959 and went on to play a central role in their scientific achievements until his death, eleven years ago tonight. As I write, two of those spacecraft, the Voyagers 1 and 2, sail the shallows of the great ocean of interstellar space. They are our species' first emissaries to depart the heliosphere, crossing the boundary where the solar wind meets the gas between the stars. Perhaps the most accomplished explorers in history, they have most recently discovered the shape of our solar system as it moves through space, and their service to humanity continues. As many of you know, each of the Voyagers carry a complex message of greetings, images, music and other sounds of Earth.

(One of those sounds is Carl's inimitable laugh. His laugh was actually the first thing I noticed about him the night we met in 1974. I remember thinking that I had never heard anything before so free and natural.)

It was also back in the late '50's that Carl first started thinking about planetary atmospheres. He was writing his Ph.D. thesis on "Physical Studies of the Planets." His thesis included his discovery of the surprisingly high temperature of Venus and his correct explanation that it was caused by a runaway greenhouse effect. Early on he began to wonder what would happen if our own moderate greenhouse effect here on Earth were to intensify as it had on Venus. He became one of the first scientists to sound the alarm on global warming and other forms of inadvertent climate modification, including the potential consequences of a major nuclear war which he named "nuclear winter."

It was nearly fifty years ago that Carl began his life-long research on the origin of life and the search for life and intelligence elsewhere in the cosmos. Back then, research on the latter subject was effectively a form of professional suicide. The scientific community viewed it as a subject beneath its dignity. Only a handful of courageous scientists, Carl among them, dared to jeopardize their careers by doing such research. Today as the numbers of newly discovered extra-solar planets steadily mount, the field of astrobiology flourishes.

Even earlier, the notebooks he filled in his teens were suffused with a passion for the values of science and democracy. He viewed the error-correcting mechanisms built into both the methodology of science and into our constitution as being on a par with the domestication of fire, the invention of agriculture and writing; among the most precious innovations ever devised by our species.

In this society dependent on science and technology, he thought that it was critically important for science to learn to communicate its insights, values and methods to everyone. At a time when "reputable" scientists rarely if ever ventured before the public, he was willing to risk his career for that also. One such effort, his 1980 "Cosmos" television series, has now been seen by a billion people worldwide. Parts of it will be broadcast in North America at 8pm EST on Christmas Day on the Discovery Science Channel. On Tuesday evenings at 9pm EST, starting January 8, 2008 the whole series will begin to run again. "Cosmos'" enduring world-wide appeal is another testament to his prophetic vision.

He believed that science must always remain scrupulously faithful to the most rigorous possible methodological standards but that we shouldn't shrink from the spiritual implications of its insights. He dreamed of a civilization rooted in our dawning understanding of nature, where skepticism and wonder went hand in hand. He didn't want to humiliate or demean the believer. He was always ready to communicate.

That voice, that laugh, the smile, the work, the love; the memory of Carl is always with me. It feels like an embrace.

Dear Friends of Carl, if you were impelled to protect the environment, attracted to read, study, teach or do science, engineering or mathematics because of something he wrote or said, please send me your stories.

May we find a way to join together to brighten up this age and to rekindle the hope that Carl Sagan's life and work can not help but inspire.